The impact of electrolytic pH on photoelectrochemical water oxidation.

Harnessing solar energy for clean and sustainable fuel production by photoelectrochemical water oxidation over different timescales has been extensively investigated. However, the light-driven photoelectrochemical water oxidation reaction for artificial photosynthesis suffers from poor photon-to-current efficiency. Herein, we demonstrate an experimental analysis of electrolytic pH on photoelectrochemical syngas production by varying the pH of the KOH and NaOH electrolytes using the N-ZnO photoelectrode and analyzing all variables. A maximum photocurrent of 13.80 mA cm-2 at 1.23 V vs. RHE with a 43.51% photon-to-current conversion efficiency was obtained at pH 13 in the aqueous NaOH electrolyte.

Efficient charge separation and improved photocatalytic activity in Type-II & Type-III heterojunction based multiple interfaces in BiOCl0.5Br0.5-Q: DFT and Experimental Insight.

The nanostructured, inner-coupled Bismuth oxyhalides (BiOX0.5X'0.5; X, X' = Cl, Br, I; X≠X') heterostructures were prepared using Quercetin (Q) as a sensitizer. The present study revealed the tuning of the band properties of as-prepared catalysts. The catalysts were characterized using various characterization techniques for evaluating the superior photocatalytic efficiency and a better understanding of elemental interactions at interfaces formed in the heterojunction. The material (BiOCl0.5Br0.5-Q) reflected higher degradation of MO (about 99.85%) and BPA (98.34%) under visible light irradiation than BiOCl0.5I0.5-Q and BiOBr0.5I0.5-Q. A total of 90.45 percent of total organic carbon in BPA was removed after visible light irradiation on BiOCl0.5Br0.5-Q. The many-fold increase in activity is attributed to the formation of multiple interfaces between halides, conjugated π-electrons and multiple -OH groups of quercetin (Q). The boost in degradation efficiency can be attributed to the higher surface area, 2-D nanostructure, inhibited electron-hole recombination, and appropriate band-gap of the heterostructure. Photo-response of BiOCl0.5Br0.5-Q is higher compared to BiOCl0.5I0.5-Q and BiOBr0.5I0.5-Q, indicating better light absorption properties and charge separation efficiency in BiOCl0.5Br0.5-Q due to band edge position. First-principles Density Functional Theory (DFT) based calculations have also provided an insightful understanding of the interface formation, physical mechanism, and superior photocatalytic performance of BiOCl0.5Br0.5-Q heterostructure over other samples.